During heart systole, its mitral valve and tricuspid valve close up, forcing intraventricular blood to flow into arteries, and meanwhile preventing intraventricular blood from reversely flow into atriums. However, backflow of blood into the atriums occurs when contraction of ventricles fails to trigger full closure of the valve cusps due to diseases such as valve sinus dilation, rapture of mitral chordae tendinae, perforation of valve cusp or prolapse of valve cusp. Annuloplasty ring implantation, as an important clinical means to reshape diseased mitral valve and tricuspid valve to maintain their normal shape and contour, can be employed to repair ventricular regurgitation and the like due to disease-induced incomplete closure of the mitral valve and tricuspid valve cusps.
Currently, the annuloplasty ring already used for clinical purposes is mainly divided into three types: soft ring, rigid ring and semi-rigid ring. The soft ring is mainly of a two-dimensional structure and a main structure thereof is mainly made of a polymer material, so that soft ring can fit well with an annulus of a valve, but the material of the soft ring is excessively soft, which is not favorable for effective closure of the valve cusps and effective plastic of the ring. And the rigid ring and the semi-rigid ring are of a two-dimensional planar structure, or a three-dimensional saddle structure designed according to the anulus of the valve, in which the latter structure is advantageous in reducing stress imposed on the valve cusps and enhancing the durability. The rigid ring usually adopts a metal material and has good support strength, but such rigid ring is not easy to bend, therefore it is unable to achieve a coordination movement with the cardiac cycle. The semi-rigid ring combines the advantages of both the soft ring and the rigid ring, and can offer good support strength through adjusting rigidity of main body of the annuloplasty ring, and meanwhile effectively adapt to variation in the ring plane of the valve caused by cardiac systole and diastole. Therefore, the semi-rigid ring is brought into limelight.
Currently, regarding the semi-rigid ring, its annular main body mainly adopts a wire with a variable diameter, in order to adjust the rigidity, and the rigidities of ring sections are controlled through adjusting the diameter of the wire, but the process to design and manufacture a mold for manufacturing such a semi-rigid ring is tedious, resulting in a complicated manufacturing process and stringent technical requirements; sometimes, its annular main body adopts a combination of metal and polymer to adjust the rigidity of the entire annuloplasty ring, where a metallic ring section and a polymeric ring section need to be matched according to rigidity requirement before being connected, and it needs to strictly control processing and connecting procedure of the metallic ring section and the polymeric ring section due to requirements for special application environment, which leads to a complex process and an increased risk of failure; and furthermore, for some of such structure designs, wear and tear often occur at the connection of the metallic and the polymeric ring sections during application, affecting the long-term use effect.